The goals for the coming year are to perfect the multiple "inert" gas elimination technique and test its accuracy and resolution in anesthetized-paralyzed dogs. Later we plan to use this technique to determine the relative contributions of increased mismatching of ventilation-perfusion ratios and pulmonary right-to-left shunt to arterial hypoxemia during anesthesia in man. BIBLIOGRAPHIC REFERENCES: Frazier, A.R., Rehder, K., Sessler, A.D., Rodarte, J.R., Hyatt, R.E.: Single-breath oxygen tests for individual lungs in awake man. J. Appl. Physiol. Vol. 40, 1976. Rehder, K., Sessler, A.D., Rodarte, J.R.: Relationship of ventilation/unit lung volume, lung volume and vertical distance down the lung in awake and anesthetized, paralyzed man. Fed. Proc. 35, 1976.